Please consider the following changes to this file:

  1. instead of ATD#99*, please use ATD\U and then add "-U #99*" to
     the /etc/ppp/peers/gprs file. Reason: some providers don't use
     this standard dialing sequence.

  2. instead of requiring the PIN to be specified in this file,
     I suggest to say AT+CPIN="$SIMPIN" or so, then to invoke chat
     like this: env SIMPIN=1234 chat -E …. Reason: the PIN is
     a parameter that should at least not appear on the command
     line.

  3. Enable the AT+CPIN line, but ignore errors from it, or make it
     conditional on the output of AT+CPIN? if possible.

These changes should allow the complete reuse of
/etc/chatscripts/gprs for all purposes.

This would require fixing #3 first.
I expect that some modems would break if sent an unexpected PIN, and
ignoring errors would not be acceptable.
I do not have a modem around, but I would accept a patch to only send
the PIN if the answer to "AT+CPIN?" says that it is needed.
This has never been a goal...

also sprach Marco d'Itri <md@Linux.IT> [2014-10-05 07:50 +0200]:

Here you go:

  # +CPIN provides the SIM card PIN
  OK              AT+CPIN? '+CPIN: READY-AT+CPIN="$SIMPIN"-OK'
                  AT+CGDCONT=1,"IP","\T","",0,0

Note that the AT+CGDCONT=1 line needs the initial OK removed. Also,
this needs to happen after AT+CFUN=1, which turns on the card, at
least for my Ericsson.

Here's a demo:

First try:

  *EMRDY: 1
  OK
  ATH
  OK
  ATE1
  OK
  AT+CFUN=1
  OK
  AT+CPIN?
  +CPIN: SIM PIN

  OK
  AT+CPIN="1234"
  OK
  AT+CGDCONT=1,"IP","apn","",0,0
  […]

Second try:

  *EMRDY: 1
  OK
  ATH
  OK
  ATE1
  OK
  AT+CFUN=1
  OK
  AT+CPIN?
  +CPIN: READY

  OK
  AT+CGDCONT=1,"IP","apn","",0,0

There probably is a reason if AT+CFUN=1 is commented by default, so it
looks like you will still have to modify the file for your hardware.